docs: def _set_blob_metadata(self, ud, metadata):
          # type: (Uploader, blobxfer.models.upload.Descriptor, dict) -> None
          """Set blob metadata
          :param Uploader self: this
          :param blobxfer.models.upload.Descriptor ud: upload descriptor
          :param dict metadata: metadata dict
          """
          blobxfer.operations.azure.blob.set_blob_metadata(ud.entity, metadata)
          if blobxfer.util.is_not_empty(ud.entity.replica_targets):
              for ase in ud.entity.replica_targets:
                  blobxfer.operations.azure.blob.set_blob_metadata(ase, metadata)